Fig. 3

Initial biases in the naïve cortex correlate with the direction angle preference that is acquired. a Left: Sketch of imaging field in ferret visual cortex at the onset of visual experience. Neurons exhibit very weak direction selectivity, as indicated by small arrows. Nevertheless, there are regions that have statistically significant biases for particular directions, such as right (green) and left (blue) as shown [35]. These biases are found even in animals that have been dark-reared [23], suggesting that they are formed independent of any visual experience, including that through the closed lids. Middle: Artificial experience of 3–6 h with moving visual stimuli is sufficient to produce the rapid emergence of direction selectivity in visual cortex. In this case, stimuli moved in one of two opposite directions (random alternation), 5 s on, 5 s off, in 20 min blocks, with a 10 min rest period. Right: Sketch of imaging field after bidirectional experience, with enhancement of direction selectivity in both regions [35]. b Left: Sketch of initial imaging field at the onset of visual experience. Middle: Animal is provided with 3–6 h of artificial experience with moving stimuli, but here the stimuli move only in a single direction. Right: Sketch of imaging field after unidirectional experience. Neurons in regions that were biased toward the “trained” direction exhibit robust increases in direction selectivity. Neurons in regions that were biased to the opposite direction showed little change. Neurons in intermediate regions could be recruited to exhibit selectivity for the trained direction [23]